import { saveAs } from 'file-saver'
import XLSX, { WorkBook, WorkSheet } from 'xlsx'

interface ICell {
    v: Date | number | boolean | string
    t: string
    z: string
}

export enum fileType {
    xlsx = "xlsx",
    xls = "xls"
}

class Workbook implements WorkBook {
    SheetNames: string[] = []
    Sheets: { [sheet: string]: WorkSheet } = {}
}

const generateArray = (table: HTMLElement) => {
    const out = []
    const rows = table.querySelectorAll('tr')
    const ranges = []
    for (let R = 0; R < rows.length; ++R) {
        const outRow = []
        const row = rows[R]
        const columns = row.querySelectorAll('td')
        for (let C = 0; C < columns.length; ++C) {
            const cell = columns[C]
            const colspanStr = cell.getAttribute('colspan')
            const rowspanStr = cell.getAttribute('rowspan')
            let colspan
            let rowspan
            if (colspanStr) {
                colspan = parseInt(colspanStr)
            }
            if (rowspanStr) {
                rowspan = parseInt(rowspanStr)
            }
            const cellValue = cell.innerText
            // Skip ranges
            ranges.forEach(function(range) {
                if (R >= range.s.r && R <= range.e.r && outRow.length >= range.s.c && outRow.length <= range.e.c) {
                    for (let i = 0; i <= range.e.c - range.s.c; ++i) outRow.push(null)
                }
            })
            // Handle Row Span
            if (rowspan || colspan) {
                rowspan = rowspan || 1
                colspan = colspan || 1
                ranges.push({
                    s: {
                        r: R,
                        c: outRow.length
                    },
                    e: {
                        r: R + rowspan - 1,
                        c: outRow.length + colspan - 1
                    }
                })
            }
            // Handle Value
            outRow.push(cellValue !== '' ? cellValue : null)
            // Handle Colspan
            if (colspan) {
                for (let k = 0; k < colspan - 1; ++k) {
                    outRow.push(null)
                }
            }
        }
        out.push(outRow)
    }
    return [out, ranges]
}

const datenum = (date: Date) => {
    return (+date - +new Date(Date.UTC(1899, 11, 30))) / (24 * 60 * 60 * 1000)
}

const sheetFromDataArray = (data: any) => {
    const ws: { [key: string]: any } = {}
    const range = {
        s: {
            c: 10000000,
            r: 10000000
        },
        e: {
            c: 0,
            r: 0
        }
    }
    for (let R = 0; R !== data.length; ++R) {
        for (let C = 0; C !== data[R].length; ++C) {
            if (range.s.r > R) range.s.r = R
            if (range.s.c > C) range.s.c = C
            if (range.e.r < R) range.e.r = R
            if (range.e.c < C) range.e.c = C
            const cell: ICell = {
                v: data[R][C],
                t: '',
                z: ''
            }
            if (cell.v == null) continue
            const cellRef = XLSX.utils.encode_cell({
                c: C,
                r: R
            })
            if (typeof cell.v === 'number') cell.t = 'n'
            else if (typeof cell.v === 'boolean') cell.t = 'b'
            else if (cell.v instanceof Date) {
                cell.t = 'n'
                cell.z = XLSX.SSF.get_table()[14]
                cell.v = datenum(cell.v)
            } else cell.t = 's'
            ws[cellRef] = cell
        }
    }
    if (range.s.c < 10000000) {
        ws['!ref'] = XLSX.utils.encode_range(range)
    }
    return ws
}

const s2ab = (s: string) => {
    const buf = new ArrayBuffer(s.length)
    const view = new Uint8Array(buf)
    for (let i = 0; i !== s.length; ++i) {
        view[i] = s.charCodeAt(i) & 0xFF
    }
    return buf
}
/**
 * 导出页面上的Table变为excel
 * @param id Table Element Id
 */
export const exportTable2Excel = (id: string) => {
    const theTable = document.getElementById(id)
    if (theTable) {
        const oo = generateArray(theTable)
        const ranges = oo[1]

        /* original data */
        const data = oo[0]
        const wsName = 'SheetJS'

        const wb = new Workbook()
        const ws = sheetFromDataArray(data)

        /* add ranges to worksheet */
        // ws['!cols'] = ['apple', 'banan']
        ws['!merges'] = ranges

        /* add worksheet to workbook */
        wb.SheetNames.push(wsName)
        wb.Sheets[wsName] = ws

        const wbout = XLSX.write(wb, {
            bookType: 'xlsx',
            bookSST: false,
            type: 'binary'
        })

        saveAs(new Blob([s2ab(wbout)], {
            type: 'application/octet-stream'
        }), 'test.xlsx')
    }
}
/**
 * 根据格式化数据导出excel
 * @param header 表头
 * @param data 数据源
 * @param filename 文件名称
 * @param multiHeader n+1级表头
 * @param merges 合并
 * @param autoWidth 自适应宽度
 * @param bookType 生成的excel的文件类型
 */
export const exportJson2Excel = (header: string[], data: any, filename = 'excel-list', multiHeader: string[][] = [], merges: any[] = [], autoWidth = true, bookType : fileType = fileType.xlsx ) => {
    data = [...data]
    data.unshift(header)
    for (let i = multiHeader.length - 1; i > -1; i--) {
        data.unshift(multiHeader[i])
    }

    const wsName = 'SheetJS'
    const wb = new Workbook()
    const ws = sheetFromDataArray(data)

    if (merges.length > 0) {
        if (!ws['!merges']) {
            ws['!merges'] = []
        }
        merges.forEach(item => {
            ws['!merges'].push(XLSX.utils.decode_range(item))
        })
    }

    if (autoWidth) {
        const colWidth = data.map((row: any) => row.map((val: any) => {
            if (val == null) {
                return {
                    wch: 10
                }
            } else if (val.toString().charCodeAt(0) > 255) {
                return {
                    wch: val.toString().length * 2
                }
            } else {
                return {
                    wch: val.toString().length
                }
            }
        }))
        const result = colWidth[0]
        for (let i = 1; i < colWidth.length; i++) {
            for (let j = 0; j < colWidth[i].length; j++) {
                if (result[j].wch < colWidth[i][j].wch) {
                    result[j].wch = colWidth[i][j].wch
                }
            }
        }
        ws['!cols'] = result
    }

    // Add worksheet to workbook
    wb.SheetNames.push(wsName)
    wb.Sheets[wsName] = ws

    const wbout = XLSX.write(wb, {
        bookType: bookType as any,
        bookSST: false,
        type: 'binary'
    })

    saveAs(new Blob([s2ab(wbout)], {
        type: 'application/octet-stream'
    }), `${filename}.${bookType}`)
}
